Corynebacterium

Corynebacterium

• Corynebacterium

• C. diphtheriae

• Disease

• Diphteria

• Opportunistic infections by other Corynebacterium species (dipheroids)

Club-shaped also V- or L-shaped

• Club-shaped also V- or L-shaped

• Beaded appearance

• Methachromatic granules (Albert staining)

• Nonmotile

• no capsule

• Facultative anaerobic.

• Classified in CNM group.

Gravis

• Gravis

• Mitis

• Intermedius

• Belfanti

Common diphtheria (Nasopharyngitis)

• Common diphtheria (Nasopharyngitis)

• Incubation period of 2–5 days.

• Fibrinous exudate “pseudomembrane”

• Sore throat, fever, Enlargement of neck lymph nodes and neck edema. Irregulatory of cardiac rhythm, difficulties with vision, speech and swallowing.

• Corrosion of myelin sheaths in the central and peripheral nervous system leading to degenerating motor control

Cutanous diphtheria

• Cutanous diphtheria

• (a secondary infection)

• Antibody production: Blocking the fragment B and so preventing entry into the cell.

Humans the only natural host

• Humans the only natural host

• C. diphtheriae reside in the upper respiratory tract

• Transmitted by airborn droplet

• Infection at the site of a pre-existing skin lesion

Invasivness

• Invasivness

• Exotoxin

Cord factor

• Cord factor

• A glycolipid inhibits eukaryotic cell oxidation.

• Nuraminidase

• Removes N-acetyl nuraminic acid from musine membranes.

Fragment B. Binding of the toxin

• Fragment B. Binding of the toxin

• Fragment A. Enzymatic activity

Nicotinamide adenine dinucleotide phosphate (NAD)

• Nicotinamide adenine dinucleotide phosphate (NAD)

Intradermal injection (0.1 mL):

• Intradermal injection (0.1 mL):

• I. Cause inflammation (4-7 days later): No antitoxin in patient

• II. No inflammation: Antitoxin is present (Immune person)

Microscopic observation (differentiation from streptococcal and vansant nasopharyngitis)

• Microscopic observation (differentiation from streptococcal and vansant nasopharyngitis)

• Isolating the organism

• Loffler’s medium

• a tellurite plate

• Tinsdal medium

• Demonstrating toxin production

• Animal inoculation

• Eleck test

• ELISA

• PCR to detect tox gene

Tracheostomy  in children (to prevent croup)

• Tracheostomy  in children (to prevent croup)

• Antitoxin

• 20000-100000 unit (Intra muscular)

• Penicillin or erythromycin

Vaccination

• Vaccination

• A combination of diphtheria toxoid, tetanus toxoid, and killed pertusis organism.

• Given at 2, 4 an 6 months of age, with a booster at 1 and 6 years of age and then each 10 years afterward. (DPT or DT)

• The toxoid is prepared by treating the exotoxin with 0.3% formaldehyde.

Small rod like “chinese character”

• Small rod like “chinese character”

• No capsule, Facultative aerobic.

• Tumbling movement. Movement in 25 c

• Growing in 4c

• Small and smooth colony on blood with a narrow zone of beta-hemolysis

• Biochemical tests: Fermentation, Catalase + Oxidase +

Meningitis and sepsis in

• Meningitis and sepsis in

The organism is distributed worldwide in animals, plants and soil.

• The organism is distributed worldwide in animals, plants and soil.

• Transmission to human by contact with animals or their feces

• unpasteurized milk

• contaminated vegetables.

• Endogenously from gasterointestinal tract.

E-cadherin

• E-cadherin

Microscopic observation: Diphtheroids

• Microscopic observation: Diphtheroids

• Isolation by culture:

• Blood and CSF samples on blood agar

• Colonies: Small, gray colonies with a narrow zone of beta hemolysis

Penicillin

• Penicillin

• Resistant are rare

Bacillus (Aerobic)

• Bacillus (Aerobic)

• B. antheracis, B.cereus

• Clostridum (Anaerobic)

• C. tetani, C. botulinum, C. perfringens, C. difficile

Disease

• Disease

• Anthrax (common in animal but rare in humans).

A large rod with square ends.

• A large rod with square ends.

• Frequently in chains

• A unique anti-phagocytic capsule is composed of D-glutamate.

• Non-motile (other members of the genus are motile.)

Spores persist in soil for years. Infection from animal products (hides, bristles and wool), contact with sick animal.

• Spores persist in soil for years. Infection from animal products (hides, bristles and wool), contact with sick animal.

• Portals of entry: skin, mucous membranes, and respiratory tract.

A typical lesion: A painless ulcer with black, necrotic eschar. Local edema.

• A typical lesion: A painless ulcer with black, necrotic eschar. Local edema.

• Untreated cases progress to bacteremia and death.

• Woolsorter’s disease (pulmonary anthrax) is a life threatening pneumonia (by inhalation of spores).

Invasiveness

• Invasiveness

• Exotoxin

• Anthrax toxin, has 3 components:

• Protective antigen

• Lethal factor: In the presence of protective antigen is rapidly fatal for mice. The action is unknown

• Edema factor (an exotoxin): An adenylate cyclase dependent on protective antigen for its binding and entry into the cell.

Samples: Exudate, Blood, sputum.

• Samples: Exudate, Blood, sputum.

• Direct smear: Large rods in chains. Spores not seen in smears of exudate.

• Culture and biological/biochemical tests (Sensitivity to penicillin (String of pearls test), Fermentation, gelatin hydrolysis, Motility)

• No serological tests are useful

Preventing soil contamination

• Preventing soil contamination

• Sterilizing dead animals and animal products .

• Protecting persons at risk of exposure with special clothes.

• Vaccination with cell-free vaccine for persons at high risk.

Penicillin

• Penicillin

• No resistant strain isolated

Motile

• Motile

• No capsule

• Saprophyte

Disease

• Disease

• Food poisoning

• Rare infections: Meningitis, Osteomyelitis, …

• Transmission

• Spores on grains survive during steaming and rapid frying. Spore germinated when rice is kept warm.

• Portal of entry is the gastrointestinal tract.

B. cereus produces 2 enterotoxins. Their actions is unclear.

• B. cereus produces 2 enterotoxins. Their actions is unclear.

• Clinical findings

• Emetic syndrome

• A short incubation period (4 hours) with nausea and vomiting similar to staphylococcal food poisoning.

• Diarrheal syndrome

• Involves a long incubation period (18 hours) with diarrhea and resembles clostridial gastroenteritis.

Not usually done

• Not usually done

• Treatment

• No antibiotic is given. Only symptomatic treatment

• Prevention

• Grains (specially rice) should not be reheated

An aerobic bacteria

• An aerobic bacteria

• Clostridiums tetani

• Peritricus flagella

• Terminal spore

• Disease

• Tetanus (Lockjaw)

Incubation period: 4-5 days – several weeks

• Incubation period: 4-5 days – several weeks

• Violent muscle spasms in the site of infection and then jaw)

• Lockjaw (trismus) due to rigid contraction of the jaw muscles, which prevents the mouth from opening: a characteristic known as “risus sardonicus”’.

• Low blood pressure

• Respiratory failure

Spores are widespread in soil.

• Spores are widespread in soil.

• The portal of entry is a wound site.

• Germination of spores is favoured by necrotic tissue and poor blood supply in the wound.

Tetanus toxin (tetanospasmin)

• Tetanus toxin (tetanospasmin)

• It is carried intra-axonally (retrograde) to the central nervous system, where it binds to ganglioside receptors and blocks release of inhibitory mediators (e.g. glycine, Gamma-aminobutiric acid) at spinal synapses leading to hyper reflection and spastic paralysis.

History of wound and clinical picyure

• History of wound and clinical picyure

• There is no microbiologic or serologic diagnosis.

• Organisms are rarely isolated from the wound site.

• Treatment

• Antitoxin does have a low effect

• Penicillin

• Respiratory support

• Muscle relaxants

Immunization with toxoid in childhood (2, 4, 6, 12 months ages) and every 10 years thereafter.

• Immunization with toxoid in childhood (2, 4, 6, 12 months ages) and every 10 years thereafter.

• When trauma occurs deeply:

• 1. Wound should be cleaned and debrided.

• 2. Tetanus toxoid booster should be given.

• 3. Tetanus immune globulin should be given.

• 4. Penicillin administered.

In soil ---> Alkaline vegetables/meat ---> canned/vacuum-packed ---> Spore germination ---> Toxin production ---> ingestion

• In soil ---> Alkaline vegetables/meat ---> canned/vacuum-packed ---> Spore germination ---> Toxin production ---> ingestion

Botulinus toxin

• Botulinus toxin

• Observing from the gut ---> Carrying via the blood to peripheral nerve synapses ---> Blocking release of acetylcholine ---> Paralysis

Disease: Gas Gangrene / Food Poisoning

• Disease: Gas Gangrene / Food Poisoning

• Transmission

• Pathogenesis

• Clinical findings

• Laboratory diagnosis

• Treatment

• Prevention

Soil, vegetative cells are members of normal flora in colon and vagina.

• Soil, vegetative cells are members of normal flora in colon and vagina.

• Is associated with war wounds.

Alpha toxin: Lecithinase

• Alpha toxin: Lecithinase

• Glycogen metabolism: Gas in tissues: Crepitation

• Treatment

• Penicillin

• Wounds should be debrided

• H2O2

Smear of tissue and exudate samples: large positive rods.

• Smear of tissue and exudate samples: large positive rods.

• Cultured anaerobically identified with fermentation reactions

Transmission: Soil and food. Survives cooking and grows to large numbers in reheated food, especially meat.

• Transmission: Soil and food. Survives cooking and grows to large numbers in reheated food, especially meat.

• Pathogenesis: An enterotoxin (a protein in the spore coat)

• Clinical findings:

• Incubation: 8-16 hours, then watery diarrhea with cramps and little vomiting. Resolves in 24 hours.

Treatment: Symptomatic – No antimicrobial drugs

• Treatment: Symptomatic – No antimicrobial drugs

• Prevention: cooking well

Disease

• Disease

• Transmission

• Pathogenesis

• Clinical Finding

• Laboratory diagnosis

• Treatment

• Prevention

Antibiotic-associated pseudomembranous colitis

• Antibiotic-associated pseudomembranous colitis

• Transmission

• It is a part of normal flora of gasterointestinal tract (3%)

Antibiotic (Clindamycin and ampicillin) supress drug-sensitive normal flora, allowing C. difficile to multiply: produce toxin.

• Antibiotic (Clindamycin and ampicillin) supress drug-sensitive normal flora, allowing C. difficile to multiply: produce toxin.

• Toxin mechanism is unclear

Diarrhea

• Diarrhea

• Pseudomembranes (yellow-white plaques) on the colonic mucosa.

• Visualised by sigmoidoscopy.

Toxin detectable in stool affecting on cell cultured cells.

• Toxin detectable in stool affecting on cell cultured cells.

• Inhibition of cytotoxicity by specific antibody.

Withdrew the antibiotic

• Withdrew the antibiotic

• Oral vancomycin instead along with fluids.

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